Claims that a human being lacks a soul until around 24 weeks usually rest on two ideas: the emergence of detectable brain waves, or an alleged capacity to choose for or against God. Reframed carefully, neither proposal provides a coherent or defensible basis for deciding when a human being deserves legal protection.
Appealing to brain waves and labeling the argument “scientific” does not solve the problem. Brain activity, by itself, cannot ground personhood or rights, because many non-human animals exhibit brain waves and levels of conscious experience that exceed those of a 24-week-old fetus. If brain waves were the decisive criterion, consistency would require granting legal personhood to such animals as well. Since almost no one accepts that conclusion, brain activity cannot logically function as the moral line that determines who may be killed and who must be protected.
Shifting the standard to a religious capacity—such as the ability to choose for or against God—fails for a different reason. Newborn infants lack that capacity, yet killing infants is universally regarded as morally and legally unacceptable. A criterion that excludes newborns from protection is clearly defective, and therefore cannot justify excluding the unborn either.
More fundamentally, religious beliefs—whether about souls, divine choice, or spiritual development—cannot legitimately serve as a justification for killing innocent human beings. Even if someone sincerely believes that a soul arrives at 24 weeks, that belief does not supply a principled reason why humans before that point may be intentionally killed. If neither brain waves nor religious choice-making can consistently distinguish those who must be protected from those who may be destroyed, then neither can serve as a sound standard for abortion law or ethics.
Key Takeaways
Brain waves cannot ground personhood, because using them as the threshold would imply that some animals deserve legal personhood while some humans do not.
Religious criteria like choosing for or against God fail, since they would also exclude newborn infants, which is morally unacceptable.
No religious belief about when a soul appears can justify the intentional killing of innocent human beings in law or ethics.
Arbitrary developmental thresholds, such as 24 weeks, collapse under scrutiny and cannot coherently determine who deserves protection.